Thrombolysis in pulmonary embolism: are we under-using it?

Abstract

Pulmonary embolism is a common condition leading to significant morbidity and mortality. Standard initial therapy consists of heparin treatment, which has been shown to improve the outcome. Nevertheless, 3-month mortality remains high, ranging from 10% to 17.5%, and is higher for massive PE.1–,3 Thrombolysis for acute PE remains a controversial treatment, due in part to the inadequate evidence demonstrating an improvement in outcome. Current British Thoracic Society (BTS) guidelines for thrombolysis suggest its use only in massive PE, which it defines as ‘one so severe as to cause circulatory collapse’.4 Over the last year, we have experienced four cases of pulmonary embolism that were successfully thrombolysed due to respiratory failure despite being haemodynamically stable. This led us to review some of the evidence for thrombolysis in PE, and this commentary investigates the potential for expanding the role of thrombolysis in this condition, suggesting its use in respiratory failure as well as circulatory failure. Despite being controversial, thrombolysis has several theoretical advantages over simple anticoagulation with heparin.5 It should promote faster clot lysis. Acutely, this would produce more rapid improvements in pulmonary perfusion and haemodynamic imbalances, but would also reduce chronic vascular obstruction and the potential for pulmonary hypertension. Thrombolysis would also be expected to eliminate venous thrombi, and hence reduce the incidence of recurrent emboli. The BTS guidelines for thrombolysis only for circulatory compromise are based on a present paucity of data.4 In 1995, a very small study looked at 8 patients with shock related to massive PE.6 The four patients receiving heparin died, whereas the four receiving thrombolysis survived, and it is based on this, and the poor outcome in massive PE with shock, that the recommendation is based. On unselected patients with PE, the evidence for thrombolysis is even less robust. …